diff -up libdmtx-0.7.5/test/simple_test/simple_test.c.math libdmtx-0.7.5/test/simple_test/simple_test.c
--- libdmtx-0.7.5/test/simple_test/simple_test.c.math	2018-04-06 13:19:44.000000000 +0200
+++ libdmtx-0.7.5/test/simple_test/simple_test.c	2018-04-06 13:19:52.000000000 +0200
@@ -18,6 +18,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <assert.h>
+#include <math.h>
 #include <dmtx.h>
 
 int
